1. Field of the Invention
The present invention relates to a coordinate input system and, more particularly, to a coordinate input system which is capable of detecting the status of a position designating device which has designated only the position of coordinates to be input as well as the status of various types of operation designated by the same.
2. Statement of the Related Art
Hitherto, a system has been known for detecting the status (hereafter referred to as the "pen-down status") of a position designating device which has designated only the position of coordinates to be input on a tablet. This system is arranged such that a switching means is provided in the position designating device and is turned ON (or OFF) only in the pen-down status, and timing signals based on the ON (or OFF) status of the switching means are transmitted to a position detecting circuit via a cord or by the use of ultrasonic waves or infrared ways.
However with a system of the type in which timing signals are transmitted from the position designating device via a cord, there has been a drawback in that the cord causes a hindrance to he operating efficiency of the position designating device. In addition, with a system of the type in which timing signals are transmitted by the use of ultrasonic waves or infrared rays, a transmitter, a signal generating circuit, a battery, and the like must be provided in the position designating device per se. Hence, there has been a drawback in that the arrangement of the position designating device becomes complicated and large in size and weight, thereby aggravating the operating efficiency of the position designating device.